Nonlithographic method to produce masks by selective reaction, articles produced, and composition for same

ABSTRACT

A method for forming a self aligned pattern on an existing pattern on a substrate comprising applying a coating of the masking material to the substrate; and allowing at least a portion of the masking material to preferentially attach to portions of the existing pattern. The pattern is comprised of a first set of regions of the substrate having a first atomic composition and a second set of regions of the substrate having a second atomic composition different from the first composition. The first set of regions may include one or more metal elements and the second set of regions may include a dielectric. The masking material may comprise a polymer containing a reactive grafting site that selectively binds to the portions of the pattern. The masking material may include a polymer that binds to the portions of the pattern to provide a layer of functional groups suitable for polymerization initiation, a reactive molecule having functional groups suitable for polymerization propagation, or a reactive molecule, wherein reaction of the reactive molecule with the portion of the pattern generates a layer having reactive groups, which participate in step growth polymerization. Structures in accordance with the method. Compositions for practicing the method.

CROSS REFERENCE TO RELATED APPLICATION

This application is related to the application entitled “NonlithographicMethod to Produce Self-Aligned Mask, Articles Produced by Same andComposition for Same” Ser. No. 10/287,905 by the same inventors as thepresent invention, filed on the same day as the present application, andassigned to the same assignee as the present application and which isincorporated herein by reference as if fully set forth herein.

FIELD OF THE INVENTION

This invention relates to the production of patterns on a substratehaving regions with different compositions or different surfacetreatment. More particularly, it relates to a method of producing finepatterns on substrates used in, for example, the microelectronicsindustry on which electronic devices are fabricated. It is also relatedto devices fabricated in accordance with the methods. The patterns arefabricated accurately and inexpensively without the use of lithography.The present invention also provides many additional advantages, whichshall become apparent as described below.

BACKGROUND OF THE INVENTION

A number of applications and technologies involve structures having awell-defined arrangement of chemically distinct components at thesurface of a substrate. A common example is a substrate surface havingmetal conductor regions separated by insulator regions. Normally, thesestructures are defined by patterning processes such as lithography,embossing, and stamping, and have length scales ranging from10nanometers to several microns. In many of these systems it may benecessary or highly beneficial to apply an additional component ortreatment to only one of the components at the surface. One techniquefor performing this task is through the use of a mask to protect regionswhere this additional application or treatment is not desired.Effectively, the mask material directs this treatment to the intendedsurfaces that are fully exposed. Unfortunately, typical procedures togenerate a mask by lithographic or other means can be expensive anderror prone. Thus, a method in which these conventional approaches canbe circumvented would be highly advantageous.

A particular example in which such strategies would be useful involvesintegrated circuits comprised of metal and dielectric components. It iswidely known that the speed of propagation of interconnect signals isone of the most important factors controlling overall circuit speed asfeature sizes are reduced and the number of devices per unit area isincreased. Throughout the semiconductor industry, there has been astrong drive to reduce the dielectric constant, k, of the dielectricmaterials existing between metal lines and/or to minimize the thicknessof layers having comparatively larger dielectric constants, e.g., capbarrier layers. Both of these approaches reduce the effective dielectricconstant, k_(eff), of the components between metal lines, and as aresult, interconnect signals travel faster through conductors due to areduction in resistance-capacitance (RC) delays. Unfortunately, thesestrategies are difficult to implement due to limitations in maintainingsignificant properties, i.e., mechanical, barrier, electrical, etc.,that result with a reduction in thickness or change in the chemistry ofthe layers.

SUMMARY OF THE INVENTION

This invention relates to a method to fabricate mask layers onto apre-patterned substrate having two or more chemically distinct surfaceregions. The mask layer is deposited by a selective reaction approachthat provides self-alignment of the layers. This method can apply to anytechnology or application involving a chemically or physicallyheterogeneous substrate including: interconnect structures for highspeed microprocessors, application specific integrated circuits (ASICs),flexible organic semiconductor chips, and memory storage. Otherstructures that can be fabricated utilizing this method include:displays, circuit boards, chip carriers, microelectromechanical systems(MEMS), chips for hi-thoughput screening, microfabricated fluidicdevices, etc. The utility of this method stems from a simple and robustmeans in which the replication of a patterned substrate to generate amask layer can be performed, circumventing the requirement for expensiveand error prone methods, such as lithography. Thus, the presentinvention provides an extremely advantageous alternative to the priorart techniques.

In the example of integrated circuits, the effective dielectric constantis reduced by the use of a process wherein layers are selectively placedupon the metal lines. To do this, mask layers are first applied to thedielectric or hard mask surfaces. In accordance with the invention,these layers are generated by mechanisms involving selective chemicalreactions as described below. The layers can be self-aligned such thatlithographic processes are not required to define the features. Uponself-alignment on the dielectric/hardmask surfaces, these layers, canthen be used as a mask for subsequent deposition of other layers whichserve as diffusion barriers to copper, oxygen and/or water, layers whichreduce the electromigration attributes of the metal lines, and seedlayers.

Thus, in the example of integrated circuits, the use of the self-alignedmasks allows a simplified fabrication process in which the effectivedielectric constant between metal lines can be reduced through selectiveapplication of various materials to the metal lines. This is central tomaximizing the propagation speed of interconnect signals and ultimatelyprovides faster overall circuit performance. Furthermore, this inventionleads to a higher level of protection and reliability of interconnectstructures as the errors attributed to conventional patterning methodsare eliminated and to reduced processing costs. Although the utilizationof the self-aligned masks is described for integrated circuits, thismethod is useful for any application wherein the modification of aspecific component in a pre-patterned substrate is beneficial.

Thus, the invention is directed to a process wherein a mask is appliedto a pre-patterned substrate, through selective chemical reactionsdescribed below, that replicates the underlining pattern. This mask canthen be utilized for treatment or material deposition onto specificcomponents of the pre-patterned substrate. The use of the self-alignedmasks allows a unique process in which masks can be generated withoutthe need to perform additional pattern defining steps.

Another application of this invention is its use for semiconductorpackaging substrates which are comprised of conductors (usually copper)and insulators (usually epoxy, polyimide, alumina, cordierite glassceramic and the like) disposed adjacent to each other. Commonly, theconductors must be protected from external ambients and processingexposures such as soldering and wet etching. This protection can beachieved by using the various methods of forming selective coatings onthe conductor. Alternately, selective coating on the dielectric by oneof the exemplary methods can leave the metal exposed for furtherprocessing by methods such as electroless plating to add additionalmetal layers such as nickel, cobalt, palladium, gold and others on top,without exposing the dielectrics to these process steps. The ability toaccomplish these selective modifications without the use of lithographicprocessing leads to cost reductions and is particularly advantageous inmicroelectronic packaging, which is very cost sensitive.

Although the utilization of the self-aligned masks is described formicroelectronic parts, this method is useful for any application wherebythe modification of a specific component in a pre-patterned substrate isbeneficial.

Thus, this invention is directed to a method for forming a self alignedpattern on an existing pattern on a substrate comprising applying acoating of the masking material to the substrate; and allowing at leasta portion of the masking material to preferentially attach to portionsof the existing pattern. The pattern may be comprised of a first set ofregions of the substrate having a first atomic composition and a secondset of regions of the substrate having a second atomic compositiondifferent from the first composition. The first set of regions mayinclude one or more metal elements and the second set of regions mayinclude a dielectric. The first regions may comprise copper and may bepatterned electrical interconnects.

According to the present invention, the masking material may comprise apolymer containing a reactive grafting site that selectively binds tothe portions of the pattern. The polymer may be that of an amorphouspolymeric system having chain architecture (including linear, networked,branched and dendrimeric) and may contain one or more monomeric units.The polymer may be selected from the group consisting of polystyrenes,polymethacrylates, polyacrylates, and polyesters, as well as othersmentioned below. The polymer may have a reactive functional groupserving as the grafting site, the functional group being selected fromthe group consisting of: acyl chlorides, anhydrides, hydroxys, esters,ethers, aldehydes, ketones, carbonates, acids, epoxies, aziridines,phenols, amines, amides, imides, isocyanates, thiols, sulfones, halides,phosphines, phosphine oxides, nitros, azos, benzophenones, acetals,ketals, diketones, and organosilanes (Si_(x)L_(y)R_(z,)) where L isselected from the group consisting of hydroxy, methoxy, ethoxy, acetoxy,alkoxy, carboxy, amines, halogens, R is selected from the groupconsisting of hydrido, methyl, ethyl, vinyl, phenyl (any alkyl or aryl).

The method may further comprise preparing a polymer to act as themasking material, forming a condensed phase containing the polymer, andcontacting the portions of the pattern with the condensed phase. Thecondensed phase may be a liquid. The liquid may be a solvent for thepolymer.

In accordance with another aspect of the invention , the maskingmaterial may include a reactive molecule that binds to the portions ofthe pattern to provide a layer of functional groups suitable forpolymerization initiation. The layer may be a molecular monolayer. Thereactive molecule may include a first moiety that binds to the portionsof the pattern and a second moiety that serves as a polymerizationinitiator. The first moiety that binds to the portions of the patternmay be selected from the group consisting of acyl chlorides, anhydrides,hydroxys, esters, ethers, aldehydes, ketones, carbonates, acids,epoxies, aziridines, phenols, amines, amides, imides, isocyanates,thiols, sulfones, halides, phosphines, phosphine oxides, nitros, azos,benzophenones, acetals, ketals, diketones, and organosilanes(Si_(x)L_(y)R_(z,)) where L is selected from the group consisting ofhydroxy, methoxy, ethoxy, acetoxy, alkoxy, carboxy, amines, halogens, Ris selected from the group consisting of hydrido, methyl, ethyl, vinyl,phenyl (any alkyl or aryl). The second moiety that serves as apolymerization initiator may be selected from the group consisting ofperoxides, nitroxides, halides, azos, peresters, thioesters, hydroxy;metal organics having the stoichiometry of RX where R may consist of:benzyl, cumyl, butyl, alkyl, napthalene, and X may consist of sodium,lithium, and potassium; protonic acids, lewis acids, carbenium salts,tosylates, triflates, benzophenones, aryldiazonium, diaryliodonium,triarylsulfonium, acetals, ketals, and diketones.

The method may comprise applying a reactive monomer to the layer offunctional groups, so that the reactive monomer polymerizes on the layerto form a self-aligned mask layer. The polymerization may comprise achain growth mechanism wherein polymerization proceeds through additionof a monomer to a reactive polymer. The reactive monomer may be anymolecule that polymerizes by a chain growth process and may be asubstituted ethylenic organic molecule, one of a monomeric ring, amixture of similar or dissimilar molecules that react with each other toform a covalent bond, and may be oligomeric or polymeric. The reactivemonomer may be one that polymerizes when exposed to one of a freeradical, an anion, transition metal catalyst, or a cation. The reactivemonomer may also be one that polymerizes when exposed to thermalannealing or irradiation. The reactive monomer may be selected from thegroup consisting of: dienes, alkenes, acrylics, methacrylics,acrylamides, methacrylamides, vinylethers, vinyl alcohols, ketones,acetals, vinylesters, vinylhalides, vinylnitriles, styrenes, vinylpyridines, vinyl pyrrolidones, vinyl imidazoles, vinylheterocyclics,styrene, cyclic lactams, cyclic ethers, cyclic lactones, cycloalkenes,cyclic thioesters, cyclic thioethers, aziridines, phosphozines,siloxanes, oxazolines, oxazines, and thiiranes.

The method may further comprise applying the reactive monomer in acondensed phase, and contacting the portions of the pattern with thecondensed phase. The condensed phase may be a liquid. The liquid may bea solvent for the polymer. Alternatively, the method may furthercomprise applying the reactive monomer in a vapor phase.

In accordance with another aspect of the invention, the masking materialmay include a reactive molecule having functional groups suitable forpolymerization propagation. The reactive molecule may be comprised of afirst moiety that will bind the reactive molecule to the portions of theexisting pattern, and a second moiety that serves as a monomeric unit.The first moiety may be selected from the group consisting of: acylchlorides, anhydrides, hydroxys, esters, ethers, aldehydes, ketones,carbonates, acids, epoxies, aziridines, phenols, amines, amides, imides,isocyanates, thiols, sulfones, halides, phosphines, phosphine oxides,nitros, azos, benzophenones, acetals, ketals, diketones, andorganosilanes (Si_(x)L_(y)R_(z,)) where L is selected from the groupconsisting of hydroxy, methoxy, ethoxy, acetoxy, alkoxy, carboxy,amines, halogens, R is selected from the group consisting of hydrido,methyl, ethyl, vinyl, phenyl (any alkyl or aryl). The second moiety maybe comprised of a monomer, and may be selected from the group consistingof, dienes, alkenes, acrylics, methacrylics, acrylamides,methacrylamides, vinylethers, vinyl alcohols, ketones, acetals,vinylesters, vinylhalides, vinylnitriles, styrenes, vinyl pyridines,vinyl pyrrolidones, vinyl imidazoles, vinylheterocyclics, styrene,cyclic lactams, cyclic ethers, cyclic lactones, cycloalkenes, cyclicthioesters, cyclic thioethers, aziridines, phosphozines, siloxanes,oxazolines, oxazines, and thiiranes,

The reactive monomer polymerizes when exposed to one of a free radical,an anion, a transition metal catalyst, or a cation. The reactive monomermay be one that polymerizes when exposed to thermal annealing orirradiation. The polymerization of the reactive monomer with the secondmoiety of the reactive molecule, which serves as a monomeric unit,provides a mechanism where polymerization through the surface boundgroups occurs to form a self-aligned mask layer. The reactive monomermay be any monomer that polymerizes by a chain growth process and may beselected from the group consisting of dienes, alkenes, acrylics,methacrylics, acrylamides, methacrylamides, vinylethers, vinyl alcohols,ketones, acetals, vinylesters, vinylhalides, vinylnitriles, styrenes,vinyl pyridines, vinyl pyrrolidones, vinyl imidazoles,vinylheterocyclics, styrene, cyclic lactams, cyclic ethers, cycliclactones, cycloalkenes, cyclic thioesters, cyclic thioethers,aziridines, phosphozines, siloxanes, oxazolines, oxazines, andthiiranes.

The addition of initiator can be utilized for polymerization or thepolymerization can be driven thermally. The initiator may be selectedfrom the group consisting of peroxides, nitroxides, halides, azos,peresters, thioesters, hydroxy; metal organics having the stoichiometryof RX where R may consist of: benzyl, cumyl, butyl, alkyl, napthalene,and X may consist of sodium, lithium, and potassium; protonic acids,lewis acids, carbenium salts, tosylates, triflates, benzophenones,aryldiazonium, diaryliodonium, triarylsulfonium, acetals, ketals, anddiketones.

The method may further comprise applying the reactive monomer andinitiator in a condensed phase, and contacting the portions of thepattern with the condensed phase. The condensed phase may be a liquid.The liquid may be a solvent for the polymer. Alternatively, a vaporphase may be used.

In accordance with another aspect of the invention, the masking materialincludes a composition wherein polymerization proceeds by a step growthprocess whereby reactions that combine monomers and polymers having twoor more functionalities that react with each other to produce polymersof a larger molecular weight. The masking material comprises a reactivemolecule, wherein reaction of the reactive molecule with the portion ofthe pattern generates a layer having reactive groups, which participatein step growth polymerization. The reactive molecule comprises a firstmoiety that binds the reactive molecule to the portions of the pattern,and a second moiety that serves as a reaction site. The first moietythat binds to portions of the pattern may be selected from the groupconsisting of: acyl chlorides, anhydrides, hydroxys, esters, ethers,aldehydes, ketones, carbonates, acids, epoxies, aziridines, phenols,amines, amides, imides, isocyanates, thiols, sulfones, halides,phosphines, phosphine oxides, nitros, azos, benzophenones, acetals,ketals, diketones, and organosilanes (Si_(x)L_(y)R_(z,)) where L isselected from the group consisting of hydroxy, methoxy, ethoxy, acetoxy,alkoxy, carboxy, amines, halogens, R is selected from the groupconsisting of hydrido, methyl, ethyl, vinyl, phenyl (any alkyl oraryl),hydroxy. The second moiety that serves as a reaction site may beselected from the group consisting of: amines, nitriles, alcohols,carboxylic acids, sulfonic acids, isocyanates, acyl chlorides, esters,amides, anhydrides, epoxies, halides, acetoxy, vinyl, and silanols. Themethod further comprises applying a reactive monomer, having one or morefunctionalities to the layer a form a self-aligned mask layer. The oneor more functionalities react with each other to form a covalent bond.The reactive monomer may be one that polymerizes when exposed to thermalannealing or irradiation.

The reactive monomer may be comprised of at least two functional groupswhich may be dissimilar and may be a mixture of dissimilar molecules andmay be comprised of functional groups consisting of: amines, nitriles,alcohols, carboxylic acids, sulfonic acids, isocyanates, acyl chlorides,esters, amides, anhydrides, epoxies, halides, acetoxy, vinyl, andsilanols.

The method may further comprise applying the reactive monomer in acondensed phase, and contacting the portions of the pattern with thecondensed phase. The condensed phase may be a liquid. The liquid may bea solvent for the polymer. Alternatively, a vapor phase may be used. Ingeneral, a vapor phase is used only when applying the reactive monomerto functional groups, and not when polymer is applied.

The method may further comprise removing the masking material fromportions of the pattern to which it does not attach. The removing may beaccomplished by at least one of rinsing, ultrasonication, dissolution,thermolysis, irradiation, decomposition and related removal methodsknown in the art. Application of the masking material to the substratemay be accomplished by any means known in the art for example:spin-coating, dip coating, spray coating, scan coating, and using adoctor blade. Other methods may be used within the invention.

The method may further comprise chemically treating regions of thesubstrate prior to applying the coating. The chemically treating may becomprised of at least one of plasma treatment, application of anoxidizing solution, annealing in an oxidizing or reducing atmosphere,and application of a material that renders surface portions of thesubstrate, to which it is applied, hydrophobic. The chemical treatmentchanges the wetting characteristics of the regions of the substrate. Thechemically treating may comprise applying a molecule having reactivegrafting sites that can covalently bind to the dielectric surfaceincluding: acyl chlorides, anhydrides, hydroxys, esters, ethers,aldehydes, ketones, carbonates, acids, epoxies, aziridines, phenols,amines, amides, imides, isocyanates, thiols, sulfones, halides,phosphines, phosphine oxides, nitros, azos, benzophenones, acetals,ketals, diketones, and organosilanes (Si_(x)L_(y)R_(z,)) where L isselected from the group consisting of hydroxy, methoxy, ethoxy, acetoxy,alkoxy, carboxy, amines, halogens, R is selected from the groupconsisting of hydrido, methyl, ethyl, vinyl, and phenyl (any alkyl oraryl). The method may further comprise chemically treating regions ofthe substrate prior to the coating with chemicals that have an affinityto metals. The include chemicals, such as copper binding groups havingfunctional groups comprised of hydroxys, esters, ethers, aldehydes,ketones, carbonates, acids, phenols, amines, amides, imides, thioesters,thioethers, ureas, urethanes, nitriles, isocyanates, thiols, sulfones,halides, phosphines, phosphine oxides, phosphonimides, nitros, azos,thioesters, and thioethers. The functional groups can be heterocyclics,such as benzotriazole, pyridines, imidazoles, imides, oxazoles,benzoxazoles, thiazoles, pyrazoles, triazoles, thiophenes, oxadiazoles,thiazines, thiazoles, quionoxalines, benzimidazoles, oxindoles, andindolines.

The invention is also directed to a structure comprising a self alignedpattern on an existing pattern on a substrate, the self aligned patternincluding a masking material having an affinity for portions of theexisting pattern, so that the masking material preferentially reactivelygrafts to the portions of the existing pattern. The pattern may becomprised of a first set of regions of the substrate having a firstatomic composition and a second set of regions of the substrate having asecond atomic composition different from the first composition. Thefirst set of regions may include one or more metal elements and thesecond set of regions may include a dielectric. The self-aligned patternis disposed upon the second set of regions or only upon the second setof regions; that is not upon the first set of regions. The structure maycomprise at least one conductive feature, formed on the substrate, withthe substrate further comprising at least one insulating layersurrounding the conductive feature. The insulating layer may surroundthe at least one conductive feature at its bottom and lateral surfaces.The structure may further comprise at least one conductive barrier layerdisposed at, at least one interface between the insulating layer and theat least one conductive feature. The combination of the at least oneconductive feature and the insulating layers, may be repeated to form amultilevel interconnect stack.

The substrate may be one of a silicon wafer containing microelectronicdevices, a ceramic chip carrier, an organic chip carrier, a glasssubstrate, a gallium arsenide substrate, a silicon carbide substrate, orother semiconductor wafer, a circuit board, or a plastic substrate.

The invention is also directed to a composition for selectively coatinga pattern on a substrate, the composition comprising a carrier materialfor application to the substrate, and a polymer in the carrier thatreactively grafts to regions of the substrate having first chemicalcharacteristics. The polymer may be amorphous, may having any chainarchitecture (including linear, networked, branched, dendrimeric), andcan contain one or more monomeric units. The polymer may have acyclicmain chains (carbon containing backbones) and may include poly(dienes),poly(alkenes), poly(acrylics), poly(methacrylics), poly(acrylamides),poly(methacrylamides), poly(vinylethers), poly(vinyl alcohols),poly(ketones), poly(acetals), poly(vinylesters), poly(vinylhalides),poly(vinylnitriles), poly(styrenes), poly(vinyl pyridines), poly(vinylpyrrolidones), poly(vinyl imidazoles), and poly(vinylheterocyclics). Ifthe polymer has a carbocyclic main chain, it may be, for example, apoly(phenylene). The polymer may also be a main chain acyclic heteroatompolymer selected from the group of poly(oxides), poly(carbonates),poly(esters), poly(anhydrides), poly(urethanes), poly(sulfonates),poly(siloxanes), poly(sulfides), poly(thioethers), poly(thioesters),poly(sulfones), poly(sufonamides), poly(amides), poly(imines),poly(ureas), poly(phosphazenes), poly(silanes), poly(siloxanes),poly(silazanes), and poly(nitriles). The polymer may have a heterocyclicmain chain and may be selected from the group of poly(imides),poly(oxazoles), poly(benzoxazoles), poly(thiazoles), poly(pyrazoles),poly(triazoles), poly(thiophenes), poly(oxadiazoles), poly(thiazines),poly(thiazoles), poly(quionoxalines), poly(benzimidazoles),poly(oxindoles), poly(indolines), poly(pyridines) poly(triazines),poly(piperazines), poly(pyridines), poly(piperdines),poly(pyrrolidines), poly(carboranes), poly(fluoresceins), poly(acetals),and poly(anhydrides).

The polymer in the carrier may have reactive functional groups thatcovalently bond to regions of the substrate having first chemicalcharacteristics.

Other and further objects, advantages and features of the presentinvention will be understood by reference to the following specificationin conjunction with the annexed drawings, wherein like parts have beengiven like numbers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a general process flow chart for self aligned mask generationby covalent polymer attachment, in accordance with the invention.

FIG. 2 illustrates a first method for self aligned mask generation bypolymer reaction, in accordance with the invention.

FIG. 3 is a general process flow chart for self aligned mask generationby surface polymerization, in accordance with the invention.

FIG. 4 is a second method for self aligned mask generation by chainpolymerization from a surface grafted initiator, in accordance with theinvention.

FIG. 5 is a third method for self aligned mask generation by chainpolymerization from a surface grafted monomer, in accordance with theinvention.

FIG. 6 is a fourth method for self-aligned mask generation by steppolymerization from a surface grafted reactive site, in accordance withthe invention.

FIG. 7 is a cross sectional view of a semiconductor device in accordancewith the invention.

FIG. 8 is a cross sectional view of another semiconductor device inaccordance with the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In accordance with the invention, a patterned substrate containingstructures having two or more distinct components is processed by aroute whereby layers can be applied to selected component surfaces. Thislayer can be generated by a number of approaches involving selectivereactions described below and can be used as a mask layer for subsequenttreatment or material deposition onto the intended component surfaces.These structures can be sacrificial and do not generally remain in thefinal structure. The use of the masks for the generation of selfassembled barrier layers can proceed by a number of routes including:blanket deposition followed by lift-off, blanket deposition followed bychemical mechanical polishing (CMP), and enhancement of selectiveelectrochemical and electroless metal deposition processes. It will beclear to one skilled in the art that the application of a self-alignedlayer by any of the approaches described below can be used as a processto generate a selective mask.

Two general approaches exist for the self-aligned mask generation. Thepreferred embodiment of the patterned substrate is an interconnectstructure having metal 20 and dielectric surfaces 10, as describedbelow.

Referring to FIGS. 1 and 2, the process flow and process for a firstmethod, in accordance with the invention, for pattern self-replicationare illustrated, respectively. A polymer containing at least onereactive grafting site is prepared at step 2, generally in a carriersuch as a solvent. The reactive grafting site is a functional group thatforms at least one covalent bond with the dielectric surface. In somecases, the surface of the patterned substrate may be modified, at step3, to enhance preferential surface reaction in some regions of thepatterned substrate. At step 4, the polymer 100, which contains areactive grafting site A, that selectively binds to the dielectricsurface 10 through the formation of at least one covalent bond is spincoated or applied by any suitable coating method to the substratecontaining the patterned substrate. Either upon contact or withappropriate treatment, e.g., thermal annealing or inducing reaction byradiation, as at step 5, the polymer 100 containing the reactivegrafting site A reacts or interacts favorably with the intended surface.Removal of the material at step 6, e.g., rinsing with solvent, can thenbe performed to remove unbound material that may be remaining on themetal surface 20 resulting in a self-aligned mask layer located solelyon the dielectric surface 10.

Optionally, the surface characteristics of one or more of the exposedsurfaces can be chemically modified prior to application of theself-aligned mask layer to facilitate each of the methods describedabove in step 3. Either the dielectric surface 10 or the metal surface20 can be modified in this step. Chemical modification can be performedwith any combination of modification schemes including: plasmatreatment, application of an oxidizing or reducing solution, annealingin a reducing or oxidizing atmosphere, and application of a materialthat renders surface portions of the substrate, to which it is applied,to be hydrophobic or hydrophilic. Specific chemical treatments directedto the dielectric surface 10 may include applying an organosilanecomprised of Si_(x)L_(y)R_(z,) where L is selected from the groupconsisting of hydroxy, methoxy, ethoxy, acetoxy, alkoxy, carboxy,amines, halogens, R is selected from the group consisting of hydrido,methyl, ethyl, vinyl, and phenyl (any alkyl or aryl). Specific chemicaltreatments directed to the metal surface 20 may include applyingmolecules that have preferential interactions with the metal surfaceincluding molecules having the following functional groups: hydroxys,esters, ethers, aldehydes, ketones, carbonates, acids, phenols, amines,amides, imides, thioesters, thioethers, ureas, urethanes, nitriles,isocyanates, thiols, sulfones, halides, phosphines, phosphine oxides,phosphonimides, nitros, azos, thioesters, thioethers, benzotriazole,pyridines, imidazoles, imides, oxazoles, benzoxazoles, thiazoles,pyrazoles, triazoles, thiophenes, oxadiazoles, thiazines, thiazoles,quionoxalines, benzimidazoles, oxindoles, indolines, nitrogenouscompounds, ans phosphoric acids.

In this first method, the polymer 100 containing a reactive graftingsite A can be amorphous, may have any chain architecture (includinglinear, networked, branched, dendrimeric), and can contain one or moremonomeric units. The polymer may have acyclic main chains (carboncontaining backbones) and may include poly(dienes), poly(alkenes),poly(acrylics), poly(methacrylics), poly(acrylamides),poly(methacrylamides), poly(vinylethers), poly(vinyl alcohols),poly(ketones), poly(acetals), poly(vinylesters), poly(vinylhalides),poly(vinylnitriles), poly(styrenes), poly(vinyl pyridines), poly(vinylpyrrolidones), poly(vinyl imidazoles), and poly(vinylheterocyclics). Ifthe polymer has a carbocyclic main chain, it may be, for example, apoly(phenylene). The polymer may also be a main chain acyclic heteroatompolymer selected from the group of poly(oxides), poly(carbonates),poly(esters), poly(anhydrides), poly(urethanes), poly(sulfonates),poly(siloxanes), poly(sulfides), poly(thioethers), poly(thioesters),poly(sulfones), poly(sufonamides), poly(amides), poly(imines),poly(ureas), poly(phosphazenes), poly(silanes), poly(siloxanes),poly(silazanes), and poly(nitriles). The polymer may have a heterocyclicmain chain and may be selected from the group of poly(imides),poly(oxazoles), poly(benzoxazoles), poly(thiazoles), poly(pyrazoles),poly(triazoles), poly(thiophenes), poly(oxadiazoles), poly(thiazines),poly(thiazoles), poly(quionoxalines), poly(benzimidazoles),poly(oxindoles), poly(indolines), poly(pyridines) poly(triazines),poly(piperazines), poly(pyridines), poly(piperdines),poly(pyrrolidines), poly(carboranes), poly(fluoresceins), poly(acetals),and poly(anhydrides).

The materials are designed with reactive functional groups A, orreactive grafting sites which may be selected from the group consisting: acyl chlorides, anhydrides, hydroxys, esters, ethers, aldehydes,ketones, carbonates, acids, epoxies, aziridines, phenols, amines,amides, imides, isocyanates, thiols, sulfones, halides, phosphines,phosphine oxides, nitros, azos, benzophenones, acetals, ketals,diketones, and organosilanes (Si_(x)L_(y)R_(z,)) where L is selectedfrom the group consisting of hydroxy, methoxy, ethoxy, acetoxy, alkoxy,carboxy, amines, halogens, R is selected from the group consisting ofhydrido, methyl, ethyl, vinyl, and phenyl (any alkyl or aryl), thatcovalently bind to the dielectric surface 10. These film structures canthen be used as a mask for further processing as described previously.

Referring to FIG. 3, the process flow for the second, third, and fourthmethods for pattern self-replication, in accordance with the invention,is illustrated. Also referring to FIGS. 4-6, but first to FIG. 3, thesecond, third, and fourth methods use a material that selectively reactswith the dielectric surface 10 and is subsequently used to generate amask layer through polymerization of a monomer or telomer system.Optionally, the chemical modification of either the dielectric surface10 or metal surface 20, as described previously, can be first performedat step 11. This method involves, at step 12, a covalent anchoring of areactive molecule onto the dielectric surface 10 followed by a reaction,at step 14, with a polymerizable group (monomer, macromonmer, telomer)to generate a self aligned mask layer 500. Optional steps includerinsing with a solvent 13 between steps 12 and 14, exposure to heat orradiation at step 15, and rinsing with a solvent at step 16, as morefully described below.

Both the second and third methods involve a chain growth mechanismwherein polymerization proceeds primarily through addition of monomer toa reactive polymer. For either of these methods, the chemicalmodification of either the dielectric surface 10 or metal surface 20, asdescribed previously, can be first performed.

Referring to FIG. 4, the second method involves polymerization from asubstrate grafted initiator. If the reactive molecule has a moiety thatcan serve as a polymerization initiator I, attachment of the reactivemolecule to the dielectric surface 10 generates a layer havingfunctional groups suitable for polymerization initiation 200.Application of reactive monomer to the layer having functional groupssuitable for polymerization initiation 200 results in a self alignedmask layer 500 through polymerization from the surface.

For the second method, the reactive molecule is comprised of a firstmoiety that will bind the reactive molecule to the dielectric surface 10and a second moiety that will serve as a polymerization initiator. Thefirst moiety allowing covalent bonding to the dielectric surface mayinclude reactive grafting sites, selected from the group including acylchlorides, anhydrides, hydroxys, esters, ethers, aldehydes, ketones,carbonates, acids, epoxies, aziridines, phenols, amines, amides, imides,isocyanates, thiols, sulfones, halides, phosphines, phosphine oxides,nitros, azos, benzophenones, acetals, ketals, diketones, andorganosilanes (Si_(x)L_(y)R_(z,)) where L is selected from the groupconsisting of hydroxy, methoxy, ethoxy, acetoxy, alkoxy, carboxy,amines, halogens, R is selected from the group consisting of hydrido,methyl, ethyl, vinyl, and phenyl (any alkyl or aryl). The second moietyserving as a polymerization initiator may include, peroxides,nitroxides, halides, azos, peresters, thioesters, hydroxy; metalorganics having the stoichiometry of RX where R may consist of: benzyl,cumyl, butyl, alkyl, napthalene, and X may consist of sodium, lithium,and potassium; protonic acids, lewis acids, carbenium salts, tosylates,triflates, benzophenones, aryldiazonium, diaryliodonium,triarylsulfonium, acetals, ketals, and diketones. The reactive monomercan be any substituted ethylenic organic molecule or monomeric ring thatpolymerizes under a number of conditions (free radical, anionic,cationic, etc.) and can include: dienes, alkenes, acrylics,methacrylics, acrylamides, methacrylamides, vinylethers, vinyl alcohols,ketones, acetals, vinylesters, vinylhalides, vinylnitriles, styrenes,vinyl pyridines, vinyl pyrrolidones, vinyl imidazoles,vinylheterocyclics, styrene, cyclic lactams, cyclic ethers, cycliclactones, cycloalkenes, cyclic thioesters, cyclic thioethers,aziridines, phosphozines, siloxanes, oxazolines, oxazines, andthiiranes.

Referring to FIG. 5, a third method, in accordance with the invention,involves polymerization from a substrate grafted monomer. If thereactive molecule is a moiety that can serve as a polymerizable monomerM, attachment of the reactive molecule to the dielectric surface 10generates a layer 300 having functional groups suitable forpolymerization propagation. Application of a reactive monomer to thelayer having functional groups suitable for polymerization propagation300 results in a self aligned mask layer 500 through polymerization fromthe surface.

For the third method, in accordance with the invention, the reactivemolecule is comprised of a first moiety that will bind the reactivemolecule to the dielectric surface 10 and a second moiety that willserve as a monomeric unit. The first moiety allowing covalent bonding tothe dielectric surface can include reactive grafting sites such as acylchlorides, anhydrides, hydroxys, esters, ethers, aldehydes, ketones,carbonates, acids, epoxies, aziridines, phenols, amines, amides, imides,isocyanates, thiols, sulfones, halides, phosphines, phosphine oxides,nitros, azos, benzophenones, acetals, ketals, diketones, andorganosilanes (Si_(x)L_(y)R_(z,)) where L is selected from the groupconsisting of hydroxy, methoxy, ethoxy, acetoxy, alkoxy, carboxy,amines, halogens, R is selected from the group consisting of hydrido,methyl, ethyl, and vinyl, phenyl (any alkyl or aryl). The second moietyserving as a monomeric unit can include, dienes, alkenes, acrylics,methacrylics, acrylamides, methacrylamides, vinylethers, vinyl alcohols,ketones, acetals, vinylesters, vinylhalides, vinylnitriles, styrenes,vinyl pyridines, vinyl pyrrolidones, vinyl imidazoles,vinylheterocyclics, styrene, cyclic lactams, cyclic ethers, cycliclactones, cycloalkenes, cyclic thioesters, cyclic thioethers,aziridines, phosphozines, siloxanes, oxazolines, oxazines, andthiiranes. The reactive monomer can be any vinyl or monomeric ring asdescribed for the second method.

Referring to FIG. 6, a fourth method, in accordance with the invention,involves a step growth mechanism, whereby polymerization proceeds byreactions that combine monomers and polymers having two or morefunctionalities that react with each other to produce polymers of largermolecular weight. For this method, the chemical modification of eitherthe dielectric surface 10 or metal surface 20, as described previously,can be first performed. This approach, as shown in FIG. 6, utilizes apolymerization scheme where the reactive molecule, having a functionalgroup R, is applied to the patterned substrate. Selective reaction ofthe reactive molecule to the dielectric surfaces 10 generates a layer400 having reactive groups, which can participate in step growthpolymerizations. Application of reactive monomers, having either one ormore S and/or T functionalities that react with each other to form acovalent bond, to the layer having reactive groups 400, results in theformation of a self aligned mask layer 500.

For the fourth method, the masking material is comprised of a firstmoiety that will bind the reactive molecule to the dielectric surface 10and a second moiety that will serve as a reaction site. The first moietyallowing covalent bonding to the dielectric surface can include,organosilanes, hydroxy, acyl chlorides, carboxylic acids acyl chlorides,anhydrides, hydroxys, esters, ethers, aldehydes, ketones, carbonates,acids, epoxies, aziridines, phenols, amines, amides, imides,isocyanates, thiols, sulfones, halides, phosphines, phosphine oxides,nitros, azos, benzophenones, acetals, ketals, diketones, andorganosilanes (Si_(x)L_(y)R_(z,)) where L is selected from the groupconsisting of hydroxy, methoxy, ethoxy, acetoxy, alkoxy, carboxy,amines, halogens, R is selected from the group consisting of hydrido,methyl, ethyl, vinyl, and phenyl (any alkyl or aryl). The second moietyserving as a monomeric unit can include, amines, nitriles, alcohols,carboxylic acids, sulfonic acids, isocyanates, acyl chlorides, esters,amides, anhydrides, epoxies, halides, acetoxy, vinyl, and silanols.Monomers used for this approach are molecules having two or morechemically identical or dissimilar functional groups that undergo stepgrowth polymerization. The functional groups can include: amines,nitriles, alcohols, carboxylic acids, sulfonic acids, isocyanates, acylchlorides, esters, amides, anhydrides, epoxies, halides, acetoxy, vinyl,and silanols.

USE OF THE ABOVE METHODS IN FABRICATING IC CHIPS, CHIP CARRIERS ANDCIRCUIT BOARDS

Several derived structures can be fabricated using the selective maskingmethods described above. In these examples, the pre-existence of asubstrate containing a pattern, the pattern comprised of a first set ofregions of the substrate surface having a first atomic compositionincluding one or more metal elements and having a second set of regionsof the substrate surface being a dielectric and having a second atomiccomposition different from the first composition, is presumed. Selectiveblocking of the dielectric surface is achieved first by one of themethods described above. The first set of regions or areas whichcomprises one or metal elements is exposed and is then subjected toprocessing steps such as electroless deposition alone, or electolessdeposition of metal, metal or dielectric deposition by sputtering,evaporation, chemical vapor deposition (CVD), plasma enhanced chemicalvapor deposition (PECVD) and the like, followed by an optionalplanarization step to form added layers only on the first set ofregions.

The structure which is produced is a microelectronic interconnectstructure comprising at least one conductive feature with a selectivecap on its top surface, formed on a substrate, with the substratefurther comprising at least one insulating layer surrounding theconductive feature at its bottom and lateral surfaces, and one or moreoptional conductive barrier layers disposed at one or more of theinterfaces between the insulator and the conductive feature.

Examples of this structural embodiment include, but are not limited to,electrically conductive interconnect wiring which is capped and embeddedin a device chip interconnect stack containing insulators, conductingand insulating barrier layers and the like; interconnect wiring ofmetals disposed on a ceramic chip carrier package; and interconnectwiring disposed on and within an organic chip or device carrier such asa printed circuit board; and thin film wiring arrays on a glass orpolymeric substrate used in the fabrication of information displays andrelated hand held devices.

Referring to FIG. 7, an interconnect structure 30 having an interlayerdielectric 31, metal wiring 32, , liner barrier layer 34, and capbarrier layer 36 is illustrated. The interconnect structure has multiplelevels 1000 comprised of via 1100 and line 1200 levels. The preferredmaterials for the interlayer dielectric 31 have low dielectric constants(k<3) and include: carbon-doped silicon dioxide (also known as siliconoxycarbide or SiCOH dielectrics); fluorine-doped silicon oxide (alsoknown as fluorosilicate glass, or FSG); spin-on glasses;silsesquioxanes, including hydrogen silsesquioxane (HSSQ), methylsilsesquioxane (MSSQ) and mixtures or copolymers of HSSQ and MSSQ; andany silicon-containing low-k dielectric. As would be known in the art,this interlayer dielectric may contain pores to further reduce thedielectric constant, and other dielectrics may be used.

Referring to FIG. 8, an interconnect structure 40 having an interlayerdielectric 31, dielectric hardmask 41, metal wiring 32, , liner barrierlayer 34, and cap barrier layer 36 is illustrated. The interconnectstructure has multiple levels 1000 comprised of via 1100 and line 1200levels. The preferred materials for the interlayer dielectric 31 havelow dielectric constants (k<3), may be an organic polymer thermoset, andmay be selected from the group SiLK™, (a product of Dow Chemical Co. ),Flare™ (a product of Honeywell), and other polyarylene ethers . As wouldbe known in the art, this organic polymer dielectric may contain poresto further reduce the dielectric constant, and other organic polymerthermoset dielectrics may be used. The preferred materials for thedielectric hardmask 41 include: silicon carbides, carbon-doped silicondioxide (also known as silicon oxycarbide or SiCOH dielectrics);fluorine-doped silicon oxide (also known as fluorosilicate glass, orFSG); spin-on glasses; silsesquioxanes, including hydrogensilsesquioxane (HSQ), methyl silsesquioxane (MSQ) and mixtures orcopolymers of HSQ and MSQ; and any silicon-containing dielectric.

Applications of the inventive methods to form selective cap barrierlayers 36 on patterned metal interconnects are now described inreference to the structures shown in FIGS. 7 and 8 which may be producedusing any of the methods described herein. The structures may begenerated through a series of steps known in the art involvingphotolithography; dielectric deposition by spin coating or chemicalvapor deposition; metal deposition by electroplating, electolessplating, thermal evaporation, sputtering; planarization by chemicalmechanical polishing; wet and dry etch processes such as reactive ionetching; thermal anneals; wet and dry cleans, etc. The example givenincludes specific details, but it is evident that numerous alternatives,modifications and variations will be apparent to those skilled in theart in light of the methods descriptions given above. Various materialsmay form the selective cap (such as silicon nitride, or variousrefractory metals and compounds of said metals). Further, this inventionis not limited to constructions of any particular shape or composition.

The application of the methods described herein may be utilized afterchemical mechanical polishing steps that result in a patterned topsurface as shown in FIGS. 2, 4, 5, and 6. A preferred route to produce aself aligned mask may be to apply polystyrene (PS) having silanolreactive groups, from a toluene solution that would be applied to thepatterned surface as shown in FIG. 2 by spin coating. The silanol groupswould then covalently bind to the dielectric surfaces with thermalannealing when the wafer is placed on a hot plate at a temperature ofabout 150° C. for 1 to 5 minutes, in an inert (N₂) atmosphere. Removalof unbound PS, by rinsing with toluene, from the metal regions generatesa topography, with PS remaining on the dielectric regions.

In the next step, this polystyrene is used as the self aligned mask. Abilayer of tantalum nitride (TaN) and tantalum is then deposited bysputtering in a sputter deposition tool (known in the art) on thepatterned substrate containing the self aligned mask. The TaN/Ta bilayercontacts the metal regions and conformally coats the PS. The wafer isthen placed in a chemical mechanical polishing (CMP) tool and thebilayer is removed from the polystyrene, and is left intact on the metalregions. Removal of the remaining polystyrene is then performed usingthermal degradation by heating in an inert ambient containing<10 ppm O₂or H₂O at a temperature of 400° C. for 30 minutes, to leave theselective cap barrier layer 36 comprised of TaN and Ta only on the metalregions.

While we have shown and described several embodiments in accordance withour invention, it is to be clearly understood that the same aresusceptible to numerous changes apparent to one skilled in the art.Therefore, we do not wish to be limited to the details shown anddescribed but intend to show all changes and modifications which comewithin the scope of the appended claims.

What is claimed is:
 1. A structure comprising: a self aligned pattern ona chemically heterogeneous substrate having an existing pattern, saidself aligned pattern including a masking material having an affinity forportions of said existing pattern, so that said masking materialpreferentially reactively grafts to said portions of said existingpattern wherein said existing pattern on said heterogeneous substrate iscomprised of a first set of regions of the substrate having a firstatomic composition and a second set of regions of the substrate having asecond atomic composition different from the first composition.
 2. Thestructure of claim 1, wherein said first set of regions includes one ormore metal elements and wherein said second set of regions includes adielectric.
 3. The structure of claim 2, wherein said self-alignedpattern is disposed upon said second set of regions.
 4. The structure ofclaim 2, wherein said self-aligned pattern is disposed only upon saidsecond set of regions.
 5. The structure of claim 2, wherein saidself-aligned pattern is not disposed upon said first set of regions. 6.The structure according to claim 1, comprising at least one conductivefeature, formed on said substrate, with the substrate further comprisingat least one insulating layer surrounding said conductive feature. 7.The structure according to claim 6, wherein said insulating layersurrounds said at least one conductive feature at its bottom and lateralsurfaces.
 8. The structure according to claim 6, further comprising atleast one conductive barrier layer disposed at, at least one interfacebetween said insulating layer and said at least one conductive feature.9. A structure according to claim 6, where the combination of the atleast one conductive feature and the insulating layers, is repeated toform a multilevel interconnect stack.
 10. The structure according toclaim 9, further comprising at least one conductive barrier layerdisposed at, at least one interface between said insulating layer andsaid at least one conductive feature.
 11. The structure according toclaim 1, wherein said substrate is one of a microelectronic device chip,a ceramic chip carrier, and an organic chip carrier.